In order to use micro ultrasonic bonding technique to package polymer microfluidic chips,an auxiliary microstructure named micro energy director is designed and fabricated.The hot embossing process for PMMA (polymethyl methacrylate) substrates with both concave micro channel and convex micro energy director for ultrasonic bonding is studied.The embossing processes with different embossing temperatures are simulated using Finite Element Method (FEM).The optimized parameters are:the embossing temperature of 135 ℃,holding time of 200 s,and the embossing pressure of 1.65 MPa.The experimental results show that the replication error between experiments and simulations is less than 2％ and the replication accuracy of the microstructure is more than 96％.The study offers a method for quick optimizing parameters for hot embossing both concave and convex microstructures.